The most reliable way I can think of to find out if a polynomial is factorable or not is to plug it into your calculator, and find your zeroes. If those zeroes are weird long decimals (or don't exist), then you probably can't factor it. Then, you'd have to use the quadratic formula.

What does not Factorable mean?

We could say that x2−2x−2 is not factorable over the rational numbers. That is it has no factors whose coefficients are rational numbers. However it is factorable if you allow irrational coefficients. ... In addition, if Δ is a perfect square (and a,b,c are rational) then it can be factored over the rationals.

What is Cannot be factored?

A polynomial with integer coefficients that cannot be factored into polynomials of lower degree , also with integer coefficients, is called an irreducible or prime polynomial . is an irreducible polynomial.